I would also really like to see this feature happen. I am in the process of converting over to Linux and plan to use beryl, but I also want to keep my current monitor configuration from my windows install, the left monitor normal and the right monitor rotated. The right monitor is also has a very slightly lower vertical resolution so that I can quickly move my mouse to the top right corner of the screen to close any full screen window. If anyone finds a way to get beryl and single monitor rotation working, please let us know.